How to Check a MOSFET Using a Digital Multimeter ... How to Check N Channel Mosfets. 1) Set the DMM to the diode range. 2) Keep the mosfet on a dry wooden table on its metal tab, with the printed side facing you and leads pointed towards you. 3) With a screwdriver or meter probe, short the gate and drain pins of the mosfet. This will initially keep the internal capacitance of the device completely discharged. How to easily test an N CHANNEL or P CHANNEL MOSFET using ... Here are the steps to test an N CHANNEL mosfet with just a multimeter ( applies to P CHANNEL too, just swap and – ), of course the MOSFET has to be disconnected completely. Make sure you are not wearing shoes and so that you don’t have any electrostatic charge, FETs are very delicate to ESD. How to Troubleshoot a MOSFET Transistor | Our Pastimes N Channel MOSFET. Turn the multimeter on and set it to read resistance at the x1,000 ohm range. Connect the meter’s negative, or black, probe tip to the MOSFET’s source lead and the positive tip to the gate lead. The meter should show a very high resistance, possibly indicating “OF” or a similar infinite resistance code. How to Build an N Channel MOSFET Switch Circuit N Channel MOSFET Circuit Schematic. If you are using a 6V DC motor or buzzer, then you connect 6V to the drain terminal. If you are powering a 12V motor or buzzer, then you connect 12V. Since the buzzer we are using in this circuit requires 6V, 6V is connected to the drain terminal. How to test MOSFET? androiderode Now move the positive meter probe to the drain. You should get a low reading. The MOSFET’s gate capacitance has been charged up by the meter and the device is turned on. Step 3. With the meter positive still connected to the drain, touch a finger between source and gate (and drain if you wish, it matters not).